1. Field of the Invention
The present invention relates to an information recording apparatus including an actuator which has a head arm for holding a recording/reproducing head for a recording medium and which loads and unloads the head arm for the recording medium by swinging. More particularly, the present invention relates to an information recording apparatus including a function for preventing the actuator from being swung accidentally toward the recording medium side when the apparatus is subjected to an external shock in a state that the actuator is located at a shunt position.
2. Description of the Related Art
As a shunt position of an actuator at non-operating, a ramp block is arranged on a periphery of a disc. Holding the actuator on the ramp block prevents a slider from moving accidentally to a data area of the disc. This is done to avoid adsorbing the slider onto the disc surface during stoppage or damaging the data area.
It is required that the actuator is held at a shunt position also when the apparatus is subjected to an external shock at non-operating. In particular, in a magnetic disc apparatus carried on a portable personal computer such as a notebook computer, a high reliability to cope with the shock is required at non-operating.
As measures against a shock, it is considered to provide an inertia lever and a latch lever. When the apparatus is subjected to an external shock, the inertia lever is swung by the inertia, the swung inertia lever is engaged with the latch lever, and the latch lever is caused to move to a swing locus of the actuator, thereby latching the actuator by the latch lever. This holds the actuator at a shunt position in spite of the shock. This function is exhibited in a clockwise direction or in a counterclockwise direction.
On the other hand, the actuator may excessively swing in a load direction or in an unload direction exceeding a limit of its original swing range due to some unusual condition such as an abnormal run of a voice coil motor during the operation of the apparatus. At this time, in order to prevent the actuator from hitting a spindle motor or other areas of the apparatus, crash stops are provided. The crash stops has two ones: one in a load direction side; and another in an unload direction side.
In order to restrain the accidental swing of the actuator due to a shock, using two elements of the inertia lever and the latch lever causes the reliability of operation to become unstable.
The inertia lever has a lager mass than that of the latch lever, so that the inertia lever, when subjected to a shock, swings earlier than the latch lever. The latch lever having a smaller mass swings later.
There is a time difference in the start of swing between both levers as described above, and the actuator is not engaged with the latch lever in a stationary state at the shunt position. This brings about a possibility that the latch operation of the actuator by the latch lever fails. In particular, when the actuator hits the crash stops, thus causing a rebound thereof there becomes higher a possibility that the latch operation fails.
The fact that the latch mechanism consists of two elements of the inertia lever and the latch lever to cause the each structure to become complex, and that two crash stops are required, as a whole, leads to an increased structural complex and an increased cost.
Although the above-mentioned problems are associated with a magnetic disc apparatus, the problems can be addressed by applying them not only to a case where the recording medium is a magnetic disc, but also widely to general information recording apparatuses.